Impact element actuating means



1938- B. w. SNODGRASS 2,126,828

IMPACT ELEMENT ACTUATING MEANS Filed Nov. 26, 1934 2 Sheets-Sheet 1 Wye/War Aug. 16, 1938. B. w. SNODGRASS IMPACT ELEMENT ACTUATING MEANS Filed NOV. 26, 1934 2 Sheets-Sheet 2 Patented Aug 16, 1938 UNITED STATES PATENT OFFICE IMPACT ELEMENT ACTUATING MEANS Benjamin W. Snodgrass, Denver, 0010.

Application November 26, 1934, Serial No. 754,764

4 Claims.

This invention relates to improvements in method and means for actuating an impact element in a manner to do useful work, and has as a prime object to provide a novel method of impact element actuation susceptible of practical development through various means whereby the relative eificiency of an impact element may be greatly enhanced.

A further object of the invention is to provide a novel method of impact element actuation wherein the normally adverse reactions of a reciprocating impact element are utilized to enhance the relative efficiency of such. element.

A further object of the invention is to provide a novel method of impact element actuation wherein inertia factors of a rapidly reciprocating impact element are made freely effective to enhance the relative eiTiciency of such element.

A further object of the invention is to provide a novel method of impact element actuation wherein uniformly intermittent power impulses are repetitiously applied to maintain a reciprocating impact element in a uniform cycle of motion.

A further object of the invention is to provide a novel method of impact element actuation wherein power impulses are applied to a reciprocable impact element only while the latter is in motion, thus relieving the power unit of excessive static loads.

A further object of the invention is to provide a novel method of impact element actuation wherein power applied to impel a reciprocable impact element in one direction is converted to effect useful work in the opposite direction.

A further object of the invention is to provide a novel method of impact element actuation wherein a reciprocable impact element is released from all mechanical restraints during its work stroke.

A further object of the invention is toprovide a novel method of impact element actuation wherein is employed an improved manner of applying power to effect reciprocation of an impact element.

A further object of the invention is to establish an improved method of transposing the energy developed in rotary motion to energy of reciprocation free from all connection with the energydeveloping rotary motion during the work phase of reciprocation and capable of imparting acceleration to the momentum of a reciprocating element with a consequent component of reciprocation deriving from the angular velocity of such rotating element; also to establish an operative principle wherein kinetic energy of a power-accelerated reciprocable element acts through abutment means at the power-accelerated end of its travel to reverse direction of such energy to effect useful work and reacts from the work element acted upon to again reverse direction of the energy and initiate acceleration of the reciprocable element away from the work element and in the direction of its power acceleration.

A further object of the invention is to provide improved means for mounting and actuating an impact element to do useful work.

A further object of the invention is to provide improved means for mounting and actuating an impact element for practical functioning as a mechanical hammer.

A further object of the invention is to provide improved means wherethrough a novel method of impact element actuation may be given practical effect.

My invention consists in the novel method, and in the construction, arrangement and combination of elements wherethrough such method is given practical effect, hereinafter set forth, pointed out in my claims and illustrated by the accompanying drawings, in which Figure 1 is a diagrammatic section axially of a conventionalized construction embodying my improved method of impact element actuation. Figure 2 is a sectional view similar to Figure 1 and illustrating a second conventionalized construction embodying the improved method. Figure 3 is a section axially of a mechanical hammer constructed and arranged to give practical efiect to the principles of my novel method. Figure 4 is a fragmentary detail view, partly in section, through the power head employed in the construction according to Figure 3. Figure 5 is a cross section, on an enlarged scale, taken on the indicated line 55 of Figure 3. Figure 6 is a cross section, on a further enlarged scale, taken on the indicated line 65 of Figure 3.

In the application of the improved method of impact element actuation as illustrated in the diagrammatic Figures 1 and 2, the numeral Ill designates an impact element of any desired suitable form and mass, which element it is mounted for free limited reciprocation between suitable spaced, parallel guides H and arranged to engage with its impact end against and transmit energy to a tool stem or shank I2 mounted for axial play in a suitable guideway carried in fixed relation on one end of the parallel guides I I, said stem or shank l2 being provided with a suitable tool element, such as a drill,

chisel, hammer, or the like, l3, fixed thereto. Spaced longitudinally of the guides H from the stem or shank l2 a distance greater than the length of the impact element Ill, a resilient element or assembly M is positioned in fixed relation with said guides and in obstructing relation with the path of the reciprocable element in, said resilient element or assembly l4 being arranged for engagement by the non-impact end of the element iii and limiting the travel of said element in one direction, travel in the opposite direction being limited, naturally, by engagement of the impact end of the element with the tool stem or shank. The resilient element or assembly may be of any suitable material and/ or construction and may take the form of a block of resilient material, such as rubber, fibre, or the like, or may take the form of a spring or assembly of springs, the essential character of the unit M being that of a resiliently yieldable abutment capable of absorbing and storing, with little energy loss to the supporting guides I I, the dynamic energy transmitted thereto through engagement of the impact element therewith. Thus is the impact element mounted and guided for free reciprocation between the relatively fixed abutment formed by the stem or shank element l2 and the resiliently yieldable abutment M in such manner as to react'f'rom either abutment according to the elastic nature of the abutment and the energy transmitted thereto by the reciprocating element, which arrangement establishes a very definite oscillatory cycle for the impact element variable in its time period for a given mass of impact element and a given construction of abutments only as the acceleration imparted to said impact element may vary. To initiate the oscillatory cycle of the impact element and to maintain said cycle after energy loss from the impact element to the tool stem or shank, suitable mechanical power means are provided for acceleration of the impact element intermediate the limiting abutments, such acceleration, in the interest of utility and efiiciency, being in the direction of the resilient abutment i4. Various specific arrangements and mechanical combinations may be employed to effect the acceleration above set forth, one arrangement operable to such end being diagrammatically illustrated in Figure 1 and a slightly modified similar arrangement being shown in Figure 2. As shown in Figure 1, a suitable housing It: is formed as a fixed extension of the guides II on the side of the unit M opposite from the impact element lil, within which housing a cam plate 16 is mounted for rotation about an axis perpendicular to that of the impact element and arranged to be suitably driven in the direction indicated by the arrow A by either manual or power means, a plurality of cam bosses H, in this instance four in number, being formed on and arranged in uniformly spaced relation marginally of the face of said plate and provided with cam surfaces leading inwardly from the plate margin. A stem I8 is fixed to the non-impact end of the element It and extends axially therefrom through an opening formed through the unit 14 to overlie the outer adjacent margin of the plate IS in clearing relation with the cam bosses H, the free end of said stem 58 being formed with a terminal head l9 offset in the direction of the plate IE to lie at times in the path of the cam surfaces carried by the bosses H and arranged to clear said cam surfaces only when the impact element is closely adjacent the limit defined by the unit I 4. With the foregoing arrangement, rotation of the plate I 6 in the direction indicated acts to engage one of the cam surfaces carried by said plate beneath the offset head l9 and to impart acceleration through such engagement to said head, stem l8 and impact element If! in the direction of the unit M, the head l9 releasing from its engagement with the cam surface just prior to engagement between the impact element and unit M, so that the dynamic energy of the impact element, alone, acts to compress the unit 14, the effect being the same as though the impact element was freely thrown against such unit. Engagement of the impact element with the unit M, with consequent compression of the latter, stores the dynamic energy of the impact element in the resilient unit, which, upon recovery from such compression, returns such energy to the impact element and propels the latter in the opposite direction and toward the stem or shank H, where, through impact engagement, the energy stored in the moving element is largely expended in useful Work accomplished through the tool element E3. The reaction between the impact end of the element In and the tool stem or shank initiates a return travel of the impact element toward the unit I l, and the spacing of the cam surfaces of the plate I6 is such that engagement of the offset head l9 with the next succeeding cam surface is had only when the impact element is moving in the direction of the acceleration to be imparted by such cam surface, thus minimizing the power requirements of the cam plate and relieving the assembly of violent shock and peak loads. In the showing according to Figure 2, the power acceleration elements are essentially the same as above described, the principal differences being matters of arrangement in that the plate It of the latter showing is mounted for rotation concentric with the stem l8 and is provided with cam bosses ll marginally disposed and formed with cam surfaces inclined to the plate surface remote from the impact element in the direction of plate rotation, such rotation being as indicated by the arrow B. With such a plate and cam arrangement, the stem i8 extends through a central hole in the plate I6 and the offset head I9 thereof is projected radially across the plate surface to intersect the path of travel of the cam surfaces, the operation of the latter arrangement being in all respects identical with that previously set forth.

From the foregoing it should be obvious that with a cam spacing timed to the oscillatory cycle of a given impact element and abutment arrangement, variations in the rotational speed of the cam plate act only to vary the time period of the cycle, there being a definite relation between the impact element travel and the speed of the cam plate whereby the speed of the former becomes a function of the latter without varying the cyclic relationship. Further, it is to be noted that application of the improved method frees the impact element entirely from any limiting mechanical connections at either end of its range of travel and throughout the power or impact stroke, thus permitting utilization of the reactions produced at each end of a reciprocating cycle to initiate travel in the opposite direction and imparting projectile effect to the impact element during its travel through the power or impact stroke under the propulsion transmitted by the resilient unit M.

In the construction of that practical embodiment of the invention illustrated in Figures 3, 4, 5 and 6, a specific impact element is designated by the numeral 20 and shown as a hollow cylindrical member provided with an impact head 2| removably engaging within and closing one end of the member 20. The member 20 is provided with a plurality of longitudinal grooves or guideways 22, in this instance three in number, uniformly spaced exteriorly of its circumference and each extending through the major portion of the length of said member, in each of which grooves 22 a pair of spaced, alined, anti-friction bearings 23 projecting inwardly in adjustably fixed relation from a hollow cylindrical housing 24 engage to position and slidingly support the member 20 for reciprocation within and axially of said housing. The bearing units 23 may be of any suitable specific construction and are preferably arranged for independent adjustment radially of the housing 24, the construction shown comprising an annular ball race 25 disposed within and to slide axially of a sleeve 26 opening radially through the housing 24 and engaged by a retainer 21 adjustably engaging within said sleeve 26, the race 25 housing a suitable set of bearing balls 28 which in turn ride on and bear against a bearing ball 29 received in one of the grooves 22, thus supporting the member 28 within and for reciprocation axially of the housing 24 with a minimum of frictional loss. Adjacent the impact head end of the member 20 the housing 24 is obstructed by a perpendicularly arranged partition 3U suitably held in fixed relation within said housing, which partition suitably supports a cone spring 3| converging toward the impact head end of the member 28 to receive and absorb impact from the latter when the tool element or shank normally in the path of the said member is misplaced or absent. Within the housing 24 on that side of the partition 38 opposite to the cone spring 3| is positioned a suitable tool holder or chuck 32, preferably mounted for free rotation about its axis in suitable anti-friction bearings 33 and provided with an axial bore registering with similar openings in the partition 30 and cone spring 3| and adapted to receive a tool shank or stem 34' freely slidable therethrough and thereby positioned wi h its inner end in the path of travel of the member 28. To rotatably engage the tool shank 34 with the chuck 32 and to limit inward extension of said tool shank relative to the housing 24, radial notches 35 are formed in the outer surface of said chuck communicating with the chuck bore, which notches are arranged to receive suitable lugs or fingers 36 formed on the tool shank 34. A suitable cap 37 may be secured to the housing 24 adjacent the chuck 32 to enclose and protect the latter, said cap being provided with a notched aperture registering with the chuck bore, through which aperture the tool shank 34 may be removed and replaced as well as supported and guided during operation of the hammer assembly. At that end of the housing 24 opposite to the tool end above described, the said housing is obstructed by a suitable partition 38 spaced from the partition 38 a distance considerably in excess of the length of the member 20. A retainer cup 39 is fitted closely within the housing 24 and arranged with its base bearing against the partition 38 and its open end directed toward the member 20, said cup 39 housing an expansive coil spring element 48 in axial alinement with the member 20 and positioned for engagement at times by the non-impact end of said member,

said member being thus mounted for reciprocation between the spring element 48 and tool shank 34. Secured to and continuing the housing 24 beyond the partition 38 a second housing 4| defines a cylindrical chamber in axially perpendicular relation with said housing 24, one end wall of said housing 4| being positioned adjacent and in parallel relation with the axis of the housing 24 and provided with guideways 42 spaced on opposite sides of and parallel with the axis of said housing 24. Engaging between the guideways 42 and slidingly mounted therein for travel diametrically of the housing 4| is mounted a cross-head 43, from Which latter a pull-rod 44 extends through the partition 38 and axially of the cup 39 and spring element 48 to swivel connection of its other'end with the non-impact end of the member 28. Fixed to one end of and in perpendicular relation with a shaft 45 journaled for rotation axially of the chamber defined by the housing 4|, a cam plate or disc 46 is rotatably positioned with its face in spaced parallelism with the plane of the guideways 42, said cam plate being provided with a plurality of cam bosses 41, in this instance three in number, uniformly disposed about its margin and each formed with a cam surface 48 curving inwardly from the margin of the cam plate in the direction of plate rotation. A suitable cam follower 49 is carried in fixed relation with the cross head. 43 and extends therefrom toward the face of the cam plate 46 to lie at times in the orbit of the cam surfaces 48, so that, as the cam plate is rotated about its axis, the first cam surface 48 engages the follower 49 and moves the latter, and consequently the cross-head 43 and attached elements, diametrically, of the housing 4| and axially of the housing 24, the cam surfaces 48 being relatively short and arranged to release the follower 49 after relatively brief travel of the cross-head. Any suitable means may be employed for manual or power rotation of theshaft 45, the arrangement shown in Figure 4 comprising a bevel gear 58 fixed to said shaft 45 in meshing, relation with a bevel pinion 5| carried by a suitably journaled shaft 52 operatively connecting with a suitable source of power (not shown).

When the improved hammer is employed in drilling operations it is expedient to provide means for rotating the drill tool and for jetting shown, a shaft 53 is journaled for rotation on,

exteriorly of and in axial parallelism with the housing 24, one end of said shaft extending through the housing 4| to terminate in a star wheel 54 positioned within said latter housing adjacent the rear face of the cam plate 46 and in spaced relation with the shaft 45. A spider 55 formed with a plurality of uniformly spaced, radial arms, in this instance three in number, is

fixed to the shaft 45 for rotation therewith and is positioned for engagement of its arm tips with the fingers of the star wheel 54 during rotation of the shaft 45, thus providing means for intermittent rotation of the shaft 53 during operation of the hammer assembly. Driving engagement'ifi between the shaft 53 and chuck 32. is had through a spur gear 55 in fixed concentric relation on said chuck and meshing with a pinion 51 loosely journaled on said shaft, said pinion having a yieldable driving connection with said shaft through a coil spring 58 telescoped on said shaft and connected at one end to said pinion and at the other end to said shaft, so that, in the event of sticking or binding of the drill tool, the rotational drive thereof may yield to avoid damage to the operating elements of the assembly. To jet airto the drill face, the drill tool is provided with an axial bore or channel, as is common practice, and the impact head is provided with an axial bore communicating with the interior of the member 20 and adapted to register with the bore in. the drill tool during engagement of the elements 2i and 34, an air piston 59 being slidingly mounted for inertia reciprocation axially within the impact end of the member 20 between a partition 28 and the element 2| and arranged, through functioning of check valves carried by said piston and partition, to pump air to the drill face immediately upon completion of each power stroke delivered to the drill tool.

The operation of the tool assembly shown and described follows and gives practical effect to the novel method first set forth. Rotation of the cam plate 46 effects engagement between a cam surface 48 and the follower 49, which, through the described connections, imparts momentum to the member 29 in the direction of the spring element 40, the cam and follower engagement being released just prior to engagement of the member 20 with the spring element, the momentum of the former acting to compress the latter, which, in turn, expands to propel the member 26 in the reverse direction for impact engagement with the tool shank 34, from which the member 26 rebounds to initiate travel toward the spring element during which travel the next cam surface 48 engages the cam follower 49 for acceleration of the reciprocating assembly and repetition of the cycle, the cam spacing being such as to synchronize with the time cycle of the reciprocating assembly. During the cycle above described, the tool rotation and air jetting is accomplished as previously set forth.

It is to be understood that the hammer assembly illustrated and above described is but typical of constructions wherethrough the novel method comprising the essence of the invention may be given practical effect, hence I wish to be understood as being limited solely by the scope of the appended claims, rather than by any details of the illustrative showing and foregoing description.

I claim as my invention 1. In a mechanical hammer, a cylindrical casing having a cup-shaped housing at its rear end, a chuck at the front end of said casing, a tool having a shank extending through said chuck into said casing, an impact member slidable longitudinally in said casing rearwardly of the tool shank, a pull rod swiveled to and extending rearwardly from the rear end of said impact member, a spring in said casing spaced rearwardly from the rear end of the impact member for the major portion of movement of the impact member and being engageable by the rear end of the impact member to check rearward movement of the impact member and impart rebound thereto, said spring surrounding said pull rod to guide reciprocating movement of the pull rod, a cross head at the rear end of said pull rod operating in said housing, a follower carried by said cross head, guides in said housing engaging opposite sides of said cross head to slidably mount the cross head for movement in the housing diametrically thereof, a rotary drive shaft extending into said housing through the peripheral wall thereof, a driven shaft rotatably mounted in said housing axially thereof and driven from said drive shaft, a disk carried by said driven shaft, and cams carried by said disk in spaced relation to each other circumferentially thereof for successively engaging said follower and moving the .cross head between the guides to exert rearward pull upon said pull rod and shift the impact rearwardly in said casing away from the tool shank.

2. In a mechanical hammer, a cylindrical casing having a cup-shaped housing at its rear end, a chuck at the front end of said casing, a tool having a shank extending through said chuck into said casing, an impact member slidable longitudinally in said casing rearwardly of the tool shank, a pull rod swiveled to and extending rearwardly from the rear end of said impact member, a spring in said casing spaced rearwardly from the rear end of the impact member for the major portion of movement of the impact member and being engageable by the rear end of the impact member to check rearward movement of the impact member and impart rebound thereto, said spring surrounding said pull rod to guide reciprocating movement of the pull rod, a cross head at the rear end of said pull rod operating in said housing, a follower carried by said cross head,

guides in said housing engaging opposite sides of said cross head to slidably mount the cross head for movement in the housing diametrically thereof, a driven shaft rotatably mounted in said housing, means for rotating said driven shaft, a disk carried by said driven shaft, cams carried by said disk adjacent margins thereof for successively engaging said follower and moving the cross head between said guides to exert pull upon said rod and shift the impact member rearwardly in the casing away from said tool shank, a

transmission shaft rotatably mounted longitudinally of said casing with its rear end extending into said housing, a star wheel carried by the rear end of said transmission shaft, arms extending radially from said driven shaft for engaging said star wheel and intermittently rotating the transmission shaft, and means for transmitting rotary motion from said transmission shaft to said chuck.

3. In a mechanical hammer, a cylindrical casing having a housing at its rear end, a chuck at the front end of said casing, a tool having a shank extending through said chuck into said casing, a tubular impact member in said casing back of said tool shank, a head at the front end of said impact member for engaging the rear end of said tool shank, ribs extending longitudinally of said impact member externally thereof and forming tracks, rollers carried by walls of said casing and engaged in said tracks to mount the impact member for free sliding movement in the casing towards and away from the tool shank, a pull rod swivelled in the rear end of said impact member and extending rearwardly therefrom into said housing, a cross head at the rear end of said pull rod operating in said housing, a spring surrounding said pull rod and mounted in the casing in position to dispose the front end of the spring in spaced relation to therear end of the impact member for the m jor portion of movement of the impact in the casing, said spring being engageable by the impact member to check rearward movement thereof and impart rebound to the impact member, a spring in said casing in front of said impact member for engaging the head at the front end of the impact member and checking forward movement thereof when the tool shank is removed, guide plates in said housing spaced transversely from each other and providing a track for said cross head extending diametrically of the housing, a follower depending from said cross head, a driven shaft rotatably mounted in said housing, a disk carried by said driven shaft under said plates, cams rising from said disk adjacent the margin thereof and spaced from each other circumferentially thereof for successively engaging said follower and moving the cross head longitudinally of the track to exert rearward pull upon said impact member 'to move the same away from the tool shank, and means for rotating said driven shaft.

4. In a mechanical hammer, a casing having a housing at its rear end, a tool shank supported in and extending axially within the front end of said casing, a resiliently-yieldable abutment disposed Within and adjacent the rear end of said casing in spaced alignment with said tool shank, an impact member within said casing between said tool shank and abutment, rollers carried by said casing adjacent said impact member, longitudinal tracks on said impact member in engagement with said rollers whereby said member is mounted for axial reciprocation between said tool shank and abutment, a pull rod secured to the rear end of said impact member and extending axially therefrom through said abutment to terminate in a cross head within said housing,

guides in said housing engaging said cross head to mount the latter for travel across said housing, a follower on said cross head, a rotatablydriven disk in said housing, and cam elements spaced marginally of said disk in position to successively engage said follower during rearward travel of said impact member and accelerate the latter in the direction of and for rebound from said abutment.

BENJAMIN W. SNODGRASS. 

